In the northeast of the country, the sandstone Ennedi Massif has been sculpted over time by water and wind erosion into a plateau featuring canyons and valleys that present a spectacular landscape marked by cliffs, natural arches and pitons. In the largest canyons, the permanent presence of water plays an essential role in the Massif’s ecosystem, sustaining flora and fauna as well as human life. Thousands of images have been painted and carved into the rock surface of caves, canyons and shelters, presenting one of the largest ensembles of rock art in the Sahara. --WHMNet's description is from WHC Site, where additional information is available.

The Ennedi Plateau, located in the North-East of Chad, in the Ennedi Region, is a sandstone bulwark in the middle of the Sahara. It is assailed by the sands on all sides, that encroach the deep valleys of the Ennedi. Only the caravans manage to cross it and this makes the region an area subject to multiple influences. The landscape has structures like towers, pillars, bridges and arches. They are a great attraction for tourists. --Wikipedia. Text is available under the Creative Commons Attribution-ShareAlike License.